size(200);
import graph;
path p=(0,0)..controls(2.20733110903,-6.37636660545)and(5.63013897615,-11.1682976194)..(10,-15)
..controls(12.3829909128,-17.0895199879)and(15.0351889726,-18.8754544743)..(18,-20)
..controls(22.8299278485,-21.8319797456)and(28.161575695,-21.810185839)..(33,-20)
..controls(36.8652152365,-18.5539180847)and(40.2115619915,-16.0399118657)..(43,-13)
..controls(49.210023991,-6.22992816795)and(52.3171286946,2.6093620821)..(56,11)
..controls(60.7927548947,21.9192713013)and(66.7609329816,32.3681821329)..(75,41)
..controls(77.7760407451,43.9083727623)and(80.788070978,46.5816686225)..(84,49)
..controls(92.3733568117,55.3044828741)and(101.931292023,59.7595334804)..(111,65)
  ..controls(112.68299108,65.9725374803)and(114.349882892,66.9726725675)..(116,68);

draw(p,linewidth(1));
draw(rotate(180)*p,linewidth(1));

pair P=point(p,0.8*length(p));
draw(P--(P.x,0),dashed);
label("$x$",P.x,S);
label("$(x,f(x))$",P,4N+W);
pair Q=rotate(180)*P;
draw(Q--(Q.x,0),dashed);
label("$-x$",Q.x,N);
label("$(-x,-f(x)$",Q,4S);
label("$O$",(0,0),SW);
axes("$x$","$y$",Arrow());
